MousePosition Scaling over a cell

Question

I'm trying to have the button follow the mouse while within the output text cell. The scaling does not exactly work as intended (fails to follow mouse correctly).

Dynamic[Overlay[{txtO, 
   Button[Style["Button", Blue, Italic, 15], Print[1]]}, All, 2, 
  Alignment -> 
   Rescale[MousePosition["CellContentsScaled", {0, 0}], {0, 1}, {-1, 
     1}]]]

Additionally, how would I make the button 1) Snap to 0,0 when the mouse is not over the output text cell anymore; and 2) disappear completely when not within the boundaries of the text cell.

The Rescale for {0,1} -> {-1,1} helped a little, but it seems I am not using CellContentsScaled correctly, as the documentation says it should range from 0 to 1 over the cell only (occasional negative numbers pop up, and values are present with the mouse outside the cell)

Answer 1

The problem here seems to be that "CellContentsScaled" doesn't relate to the size of the cell's content. Instead it relates to the size of the cell content area, i.e., the space within the displayed cell that potentially could contain something, which may be bigger than the size of the actual content.

A brute-force work-around (there should be better ways to do this):

stuffSize = 
   Overlay[{"mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm", 
           Button[Style["Button", Blue, Italic, 15], Print[1]]}, All, 2, 
           Alignment -> {0, 0}
   ] // Rasterize // ImageDimensions;

 Dynamic[
    Overlay[{"mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm", 
              Button[Style["Button", Blue, Italic, 15], Print[1]]
            }, All, 2, 
            Alignment -> 
                (-1 + 2 MousePosition["CellContentsAbsolute", {0, 0}]/stuffSize), 
            Background -> LightBlue
   ]
 ]